Field of the Invention
The invention relates to a method for detecting gaps to be bridged in the power supply of an electric rail vehicle.
In rail vehicles which are fed through a so-called third rail, i.e. conductor rails, serious interruptions in the feeding of power occur, for example in the region of points or shunts, intersections and sectioning points. As a result, in addition to the unavoidable loss of tractive force there is an interruption in the train's power supply system which is apparent, for example, in the failure of the lighting. Usually, when a gap in a conductor rail occurs a fault detection is triggered, which causes storage capacitors of a power feeder circuit to be discharged and a switch for the train's power supply system to be opened. This results in frequent starting up of drives and an increased failure rate for components such as motors, lighting systems, high-speed circuit-breakers and charging circuits for storage capacitors, etc. Furthermore, there is a disadvantageous time period after the end of the gap in the conductor rail, until the power converters serving to feed the drive motors are operational again and the train's power supply system is connected up again.
In order to overcome that problem, a method for bridging gaps in the power supply of electric, power-converter-fed rail vehicles is proposed in German Published, Non-Prosecuted Application DE 44 23 692 A1. In that publication it is assumed that a rail vehicle is provided at its two ends with current collectors for making contact with the power supply. During a time period in which the rail vehicle travels a distance that as far as possible is only slightly smaller than the distance between the front and rear current collectors, the traction power converter is changed over from a travel mode into a regenerative braking mode, i.e. a generating operating state or from the braking mode into the regenerative braking mode, as soon as a current collector which is at the front as seen in the direction of travel is not in contact with the power supply.
By virtue of that method it is possible for the rail vehicle to be capable of travelling at any speed over gaps in the power supply, which are unavoidable as a result of the topology of the track (points or shunts, intersections, isolating or separating points), with minimum interruption of the tractive force and without interruption, or with only a short interruption, of the train's power supply when the rail vehicle enters a gap in the power supply, the length of the gap and the length of the subsequent power supply (conductor rails) are unknown. Nevertheless, a reliable change-over of the power flux is ensured without jolting within the train configuration and unnecessary interruption in the train's power supply. At the same time, use is made of the fact that a reliable change-over of the power flux is possible as long as the current collector which is at the back as seen in the direction of travel is still in contact with the power supply when a gap in the power supply occurs. The components of the train configuration are protected by the method, which results in an increased service life. The comfort of passengers in the train configuration is increased since gaps in the conductor rail are travelled over without jolting and there is no unnecessary failure of the lighting system.